Marine team sounds alarm for reefs

Fourteen scientists warn of the necessity of reducing carbon dioxide to save coral

Recommendations to prevent what one scientist calls "osteoporosis of the reef" have been presented to the U.S. Coral Reef Task Force, holding its final meeting of the International Year of the Reef in Kona.

Fourteen leading climate and marine scientists and coral reef managers from the U.S. and Australia developed the "Honolulu Declaration on Ocean Acidification and Reef Management" during a workshop convened here by the Nature Conservancy two weeks ago.

Presenting the findings and recommendations to the task force at a business meeting Wednesday was Rod Salm, the conservancy's tropical marine conservation director for the Asia-Pacific area.

"The reefs of the world are at risk, and Hawaii's isolated reefs are especially vulnerable to stresses of any kind, particularly to the rapidly emerging stress brought on by climate change," he told the task force.

Suzanne Case, executive director of the conservancy in Hawaii, said: "Coral reefs are the lifeblood of our oceans, and we depend on them for survival.

"Without urgent action to limit carbon dioxide emissions and improve management of marine protected areas, even vast treasured reefs like the Great Barrier Reef and Northwestern Hawaiian Islands will become wastelands of dead coral."

The "Honolulu declaration" will be presented to the United Nations and to other national, regional and international forums to obtain commitments to address what marine scientists call "the greatest climate change threat facing coral reefs globally."

The ocean absorbs about one-third of atmospheric carbon dioxide, which combines with sea water to form carbonic acid, a process called ocean acidification. Carbonic acid erodes calcium carbonate needed by corals and other calcifying organisms to build their skeletons.

"The most important, overarching thing is to stabilize CO2 emissions," Salm said in an interview. But the scientists recognize that is "a long, convoluted political process" and that there would be a lag time even if it were accomplished because of a reservoir of atmospheric carbon dioxide dissolving in sea water, he said.

"Our goal was to work on ways we could buy time for coral reefs while CO2 levels are stabilized and eventually, hopefully, rolled back."

Atmospheric carbon dioxide is expected to double in 50 years if current emission trends continue and "ocean acidification will continue to an extent and at rates that have not occurred for tens of millions of years," Salm said.

"Ocean acidification is creeping, progressive and insidious ... a weakening of the reef structure that makes corals more vulnerable to breakage from waves and human use."

Unlike mass coral bleaching, when corals stressed by increased temperature become white, it is difficult to detect when any coral species is threatened by acidification, he said.

"The best evidence we have suggests that when atmospheric CO2 levels reach 560 parts per million, many reefs will already have moved from net growth to net erosion." The current level is 385 parts per million, he said.

"There is hope in what came out of our workshop because we have come up with practical steps people can take that are not hugely costly and will not marginalize progress made," Salm said.

The most practical policy is to mandate that climate change actions, including those addressing rising ocean acidification, sea level and temperatures, be included in marine protected management plans, he said.

On the management side, he said, "The most obvious thing that needs to be done is to put all efforts possible into reducing as many stresses on the reef systems as we can" from people, boats, overfishing, pollution and other destructive impacts.

The less stressed corals are, the more healthy and resilient they are and better able to respond to climate changes, he said.

More science also is needed to identify less vulnerable coral reefs - those most likely to survive changing ocean conditions - so they can be protected, he said.

"I think it's very encouraging," he added. "I just hope we're able to buy time long enough to get CO2 emissions under control."